Organic el display device

ABSTRACT

An organic EL display device includes a pixel electrode which is disposed in each of first to third organic EL elements, a first light emission layer which includes a first dopant material having a first absorbance peak, the first light emission layer extending over the first to third organic EL elements and being disposed above the pixel electrode, a second light emission layer which includes a second dopant material having a second absorbance peak and is disposed above the first light emission layer, a third light emission layer which is disposed above the second light emission layer, a counter-electrode which is disposed above the third light emission layer, and a hole transport layer which is formed of a material having an absorbance bottom on a shorter wavelength side than the first absorbance peak and the second absorbance peak in absorbance spectrum characteristics of the hole transport layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2008-248482, filed Sep. 26, 2008,the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic electroluminescence (EL)display device.

2. Description of the Related Art

In recent years, display devices using organic electroluminescence (EL)elements have vigorously been developed, by virtue of their features ofself-emission, a high response speed, a wide viewing angle, a highcontrast, small thickness and light weight.

In the organic EL element, holes are injected from a hole injectionelectrode (anode), electrons are injected from an electron injectionelectrode (cathode), and the holes and electrons are recombined in alight emitting layer, thereby producing light. In order to obtainfull-color display, it is necessary to form pixels which emit red (R)light, green (G) light and blue (B) light, respectively. It is necessaryto selectively apply light-emitting materials, which emit lights withdifferent light emission spectra, such as red, green and blue, tolight-emitting layers of organic EL elements which constitute the red,green and blue pixels. As a method for selectively applying suchlight-emitting materials, there is known a vacuum evaporation method. Inthe case of forming films of low-molecular-weight organic EL materialsby such a vacuum evaporation method, there is a method in which maskevaporation is performed independently for respective color pixels byusing a metallic fine mask having openings in association with therespective color pixels (see, e.g. Jpn. Pat. Appln. KOKAI PublicationNo. 2003-157973).

In the mask evaporation method using the metallic fine mask, however,pixels become very fine in the case where a high fineness (resolution)is required for the display device. As a result, a so-called colormixture defect, by which light-emitting materials of respective colorsare mixed, occurs frequently, and full-color display with high finenessis difficult realize.

BRIEF SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided anorganic EL display device comprising: an insulative substrate; a pixelelectrode which is disposed above the substrate and is disposed in eachof first to third organic EL elements having different emission lightcolors; a first light emission layer which includes a first dopantmaterial having a first absorbance peak in absorbance spectrumcharacteristics of the first dopant material, the first light emissionlayer extending over the first to third organic EL elements and beingdisposed above the pixel electrode; a second light emission layer whichincludes a second dopant material having a second absorbance peak inabsorbance spectrum characteristics of the second dopant material, thesecond light emission layer extending over the first to third organic ELelements and being disposed above the first light emission layer; athird light emission layer which includes a third dopant material, thethird light emission layer extending over the first to third organic ELelements and being disposed above the second light emission layer; acounter-electrode which extends over the first to third organic ELelements and is disposed above the third light emission layer; and ahole transport layer which is formed of a material having an absorbancebottom on a shorter wavelength side than the first absorbance peak ofthe first dopant material and the second absorbance peak of the seconddopant material in absorbance spectrum characteristics of the holetransport layer, the hole transport layer extending over the first tothird organic EL elements and being disposed between the pixel electrodeand the first light emission layer.

According to another aspect of the present invention, there is providedan organic EL display device comprising: an insulative substrate; apixel electrode which is disposed above the substrate and is disposed ineach of first to third organic EL elements having different emissionlight colors; a first light emission layer which includes a first dopantmaterial having a first absorbance peak in absorbance spectrumcharacteristics of the first dopant material, the first light emissionlayer extending over the first to third organic EL elements and beingdisposed above the pixel electrode; a second light emission layer whichincludes a second dopant material having a second absorbance peak inabsorbance spectrum characteristics of the second dopant material, thesecond light emission layer extending over the first to third organic ELelements and being disposed above the first light emission layer; athird light emission layer which includes a third dopant material, thethird light emission layer extending over the first to third organic ELelements and being disposed above the second light emission layer; acounter-electrode which extends over the first to third organic ELelements and is disposed above the third light emission layer; and ahole transport layer which has an absorbance bottom, at which anormalized absorbance is 10% or less, on a shorter wavelength side thanthe first absorbance peak of the first dopant material and the secondabsorbance peak of the second dopant material in normalized absorbancespectrum characteristics of the hole transport layer, the hole transportlayer extending over the first to third organic EL elements and beingdisposed between the pixel electrode and the first light emission layer.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 schematically shows the structure of an organic EL display deviceaccording to an embodiment of the present invention;

FIG. 2 is a cross-sectional view which schematically shows the structureof a display panel, which is adoptable in the organic EL display deviceshown in FIG. 1;

FIG. 3 shows one principle for controlling the emission light colors offirst to third organic EL elements;

FIG. 4 is a cross-sectional view which schematically shows the structureof the first to third organic EL elements shown in FIG. 3;

FIG. 5 is a graph showing light absorbance spectrum characteristics of afirst dopant material, a second dopant material and a hole transportlayer, which are adopted in the organic EL display device shown in FIG.2;

FIG. 6 is a graph for explaining a light absorbance bottom in normalizedlight absorbance spectrum characteristics;

FIG. 7 is a flow chart for describing a manufacturing method formanufacturing the first to third organic EL elements shown in FIG. 3;

FIG. 8 is a view for explaining exposure steps which are indicated by“PHOTO1 EXPOSURE” and “PHOTO2 EXPOSURE” in FIG. 7; and

FIG. 9 schematically shows another structure example of the first tothird organic EL elements.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will now be described in detailwith reference to the accompanying drawings. In the drawings, structuralelements having the same or similar functions are denoted by likereference numerals, and an overlapping description is omitted.

In the present embodiment, as an example of the organic EL displaydevice, a description is given of an organic EL display device of a topemission type, which adopts an active matrix driving method.

As shown in FIG. 1, this display device includes a display panel DP. Thedisplay panel DP includes an insulative substrate SUB such as a glasssubstrate.

Pixels PX1 to PX3 are arranged in an X direction in the named order, andconstitute a triplet (unit pixel) which is a minimum unit of a displaypixel. In a display region, such triplets are arranged in the Xdirection and Y direction. Specifically, in the display region, a pixelstring in which pixels PX1 are arranged in the Y direction, a pixelstring in which pixels PX2 are arranged in the Y direction and a pixelstring in which pixels PX3 are arranged in the Y direction are arrangedin the X direction in the named order, and these three pixel strings arerepeatedly arranged in the X direction.

Each of the pixels PX1 to PX3 includes a driving transistor DR,switching transistors SWa to SWc, an organic EL element OLED, and acapacitor C. In this example, the driving transistor DR and switchingtransistors SWa to SWc are p-channel thin-film transistors.

Scanning signal lines SL1 and SL2 extend in the X direction. Videosignal lines DL extend in the Y direction. The driving transistor DR,switching transistor SWa and organic EL element OLED are connected inseries in the named order between a first power supply terminal ND1 anda second power supply terminal ND2. In this example, the power supplyterminal ND1 is a high-potential power supply terminal, and the powersupply terminal ND2 is a low-potential power supply terminal. The powersupply terminal ND1 is connected to a power supply line PSL.

The gate electrode of the switching transistor SWa is connected to thescanning signal line SL1. The switching transistor SWb is connectedbetween the video signal line DL and the drain electrode of the drivingtransistor DR, and the gate electrode of the switching transistor SWb isconnected to the scanning signal line SL2. The switching transistor SWcis connected between the drain electrode and gate electrode of thedriving transistor DR, and the gate electrode of the switchingtransistor SWc is connected to the scanning signal line SL2. Thecapacitor C is connected between the gate electrode of the drivingtransistor DR and a constant potential terminal ND1′. In this example,the constant potential terminal ND1′ is connected to the power supplyterminal ND1.

The video signal line driver XDR and scanning signal line driver YDR aredisposed, for example, on the substrate SUB. Specifically, the videosignal line driver XDR and scanning signal line driver YDR areimplemented by chip on glass (COG). The video signal line driver XDR andscanning signal line driver YDR may be implemented by tape carrierpackage (TCP), instead of COG. Alternatively, the video signal linedriver XDR and scanning signal line driver YDR may be directly formed onthe substrate SUB.

The video signal lines DL are connected to the video signal line driverXDR. The video signal line driver XDR outputs current signals as videosignals to the video signal lines DL.

The scanning signal lines SL1 and SL2 are connected to the scanningsignal line driver YDR. The scanning signal line driver YDR outputsvoltage signals as first and second scanning signals to the scanningsignal lines SL1 and SL2.

When an image is to be displayed on this organic EL display device, forexample, the scanning signal lines SL2 are successively scanned.Specifically, the pixels PX1 to PX3 are selected on a row-by-row basis.

In a selection period in which a certain row is selected, a writeoperation is executed in the pixels PX1 to PX3 included in this row. Ina non-selection period in which this row is not selected, a displayoperation is executed in the pixels PX1 to PX3 included in this row.

In the selection period in which the pixels PX1 to PX3 of a certain roware selected, the scanning signal line driver YDR outputs, as voltagesignals, scanning signals for opening (rendering non-conductive) theswitching transistors SWa to the scanning signal line SL1 to which thepixels PX1 to PX3 are connected. Then, the scanning signal line driverYDR outputs, as voltage signals, scanning signals for closing (renderingconductive) the switching transistors SWb and SWc to the scanning signalline SL2 to which the pixels PX1 to PX3 are connected. In this state,the video signal line driver XDR outputs, as current signals (writecurrent) I_(sig), video signals to the video signal lines DL, and sets agate-source voltage V_(gs) of the driving transistor DR at a magnitudecorresponding to the video signal I_(sig).

Subsequently, the scanning signal line driver YDR outputs, as voltagesignals, scanning signals for opening the switching transistors SWb andSWc to the scanning signal line SL2 to which the pixels PX1 to PX3 areconnected, and then outputs, as voltage signals, scanning signals forclosing the switching transistors SWa to the scanning signal line SL1 towhich the pixels PX1 to PX3 are connected. Thus, the selection periodends.

In the non-selection period following the selection period, theswitching transistors SWa are kept closed, and the switching transistorsSWb and SWc are kept opened. In the non-selection period, a drivingcurrent I_(drv), which corresponds in magnitude to the gate-sourcevoltage V_(gs) of the driving transistor DR, flows in the organic ELelement OLED. The organic EL element OLED emits light with a luminancecorresponding to the magnitude of the driving current I_(drv). In thiscase, I_(drv)≅I_(sig), and emission light corresponding to the currentsignal (write current) I_(sig) can be obtained in each pixel.

In the above-described example, the structure in which the currentsignal is written as the video signal is adopted in the pixel circuitfor driving the organic EL element OLED. Alternatively, a structure inwhich a voltage signal is written as the video signal may be adopted inthe pixel circuit. The invention is not restricted to theabove-described example. In the present embodiment, use is made ofp-channel thin-film transistors. Alternatively, n-channel thin-filmtransistors may be used, with the spirit of the invention beingunchanged. The pixel circuit is not limited to the above-describedexample, and various modes may be applicable to the pixel circuit.

FIG. 2 schematically shows the cross-sectional structure of the displaypanel DP which includes the switching transistor SWa and the organic ELelement OLED.

As shown in FIG. 2, a semiconductor layer SC of the switching transistorSWa is disposed on the substrate SUB. The semiconductor layer SC isformed of, e.g. polysilicon. In the semiconductor layer SC, a sourceregion SCS and a drain region SCD are formed, with a channel region SCCbeing interposed.

The semiconductor layer SC is coated with a gate insulation film GI. Thegate electrode G of the switching transistor SWa is disposed on the gateinsulation film GI immediately above the channel region SCC. In thisexample, the switching transistor SWa is a top-gate-type p-channelthin-film transistor.

The gate insulation film GI and the gate electrode G are coated with aninterlayer insulation film II. A source electrode SE and a drainelectrode DE of the switching transistor SWa are disposed on theinterlayer insulation film II. The source electrode SE is connected tothe source region SCS of the semiconductor layer SC. The drain electrodeDE is connected to the drain region SCD of the semiconductor layer SC.The source electrode SE and drain electrode DE are coated with apassivation film PS. The passivation film PS is also disposed on theinterlayer insulation film II.

Pixel electrodes PE are disposed on the passivation film PS inassociation with the pixels PX1 to PX3. Each pixel electrode PE isconnected to the drain electrode DE of the switching transistor SWa. Inthis example, the pixel electrode PE corresponds to an anode.

A partition wall PI is formed on the passivation film PS. The partitionwall PI is disposed in a lattice shape in a manner to surround theentire periphery of the pixel electrode PE. The partition wall PI may bedisposed in a stripe shape extending in the Y direction between thepixel electrodes PE.

An organic layer ORG is disposed on each pixel electrode PE. The organiclayer ORG includes at least one continuous film which extends over thedisplay region including all pixels PX1 to PX3. Specifically, theorganic layer ORG covers the pixel electrodes PE and partition wall PI.The details will be described later.

The organic layer ORG is coated with a counter-electrode CE. In thisexample, the counter-electrode CE corresponds to a cathode. Thecounter-electrode CE is a continuous film which extends over the displayregion including all pixels PX1 to PX3. In short, the counter-electrodeCE is a common electrode which is shared by the pixels PX1 to PX3.

The pixel electrodes PE, organic layer ORG and counter-electrode CEconstitute first to third organic EL elements OLED1 to OLED3 which aredisposed in association with the pixels PX1 to PX3. Specifically, thepixel PX1 includes the first organic EL element OLED1, the pixel PX2includes the second organic EL element OLED2, and the pixel PX3 includesthe third organic EL element OLED3. Although FIG. 2 shows one firstorganic EL element OLED1 of the pixel PX1, one second organic EL elementOLED2 of the pixel PX2 and one third organic EL element OLED3 of thepixel PX3, these organic EL elements OLED1, OLED2 and OLED3 arerepeatedly disposed in the X direction. Specifically, another firstorganic EL element OLED1 is disposed adjacent to the third organic ELelement OLED3 that is shown on the right side part of FIG. 2. Similarly,another third organic EL element OLED3 is disposed adjacent to the firstorganic EL element OLED1 that is shown on the left side part of FIG. 2.

The partition wall PI is disposed between, and divides, the firstorganic EL element OLED1 and second organic EL element OLED2. Inaddition, the partition wall PI is disposed between, and divides, thesecond organic EL element OLED2 and third organic EL element OLED3.Further, the partition wall PI is disposed between, and divides, thethird organic EL element OLED3 and first organic EL element OLED1.

The sealing of the first to third organic EL elements OLED1 to OLED3 maybe effected by bonding a sealing substrate SUB2, to which a desiccant(not shown) is attached, by means of a sealant which is applied to theperiphery of the display region. Alternatively, the sealing of the firstto third organic EL elements OLED1 to OLED3 may be effected by bondingthe sealing substrate SUB2 by means of frit glass (frit sealing), or byfilling an organic resin layer between the sealing substrate SUB2 andthe organic EL element OLED (solid sealing). In the case of the fritsealing, the desiccant may be dispensed with. In the case of the solidsealing, an insulation film of an inorganic material, in addition to theorganic resin layer, may be interposed between the sealing substrateSUB2 and the counter-electrode CE. The sealing substrate SUB2 is formedof, e.g. a glass substrate.

In the present embodiment, the first to third organic EL elements OLED1to OLED3 are configured to have different emission light colors. In thisexample, the emission light color of the first organic EL element OLED1is red, the emission light color of the second organic EL element OLED2is green, and the emission light color of the third organic EL elementOLED3 is blue.

In general, the color of light in the range of wavelengths of 400 nm to435 nm is defined as purple; the color of light in the range ofwavelengths of 435 nm to 480 nm is defined as blue; the color of lightin the range of wavelengths of 480 nm to 490 nm is defined as greenishblue; the color of light in the range of wavelengths of 490 nm to 500 nmis defined as bluish green; the color of light in the range ofwavelengths of 500 nm to 560 nm is defined as green; the color of lightin the range of wavelengths of 560 nm to 580 nm is defined as yellowishgreen; the color of light in the range of wavelengths of 580 nm to 595nm is defined as yellow; the color of light in the range of wavelengthsof 595 nm to 610 nm is defined as orange; the color of light in therange of wavelengths of 610 nm to 750 nm is defined as red; and thecolor of light in the range of wavelengths of 750 nm to 800 nm isdefined as purplish red.

In this example, the range of a major wavelength between 595 nm and 800nm is defined as a first wavelength range, and the color in the firstwavelength range is set to be red. The range of a major wavelength,which is greater than 490 nm and less than 595 nm, is defined as asecond wavelength range, and the color in the second wavelength range isset to be green. The range of a major wavelength between 400 nm to 490nm is defined as a third wavelength range, and the color in the thirdwavelength range is set to be blue.

FIG. 3 schematically shows the structure of each of the first to thirdorganic EL elements OLED1 to OLED3. Each of the first organic EL elementOLED1, the second organic EL element OLED2 and the third organic ELelement OLED3 includes a pixel electrode PE, a counter-electrode CE thatis opposed to the pixel electrode PE, and an organic layer ORG that isinterposed between the pixel electrode PE and counter-electrode CE.

The first to third organic EL elements OLED1 to OLED3 are structured asdescribed below.

Specifically, the organic layer ORG is disposed on the pixel electrodePE. The organic layer ORG includes a hole transport layer HTL which isdisposed on the pixel electrode PE, a red light emission layer EML1which is a first light emission layer disposed on the hole transportlayer HTL, a green light emission layer EML2 which is a second lightemission layer disposed on the red light emission layer EML1, and a bluelight emission layer EML3 which is a third light emission layer disposedon the green light emission layer EML2. The counter-electrode CE isdisposed on the organic layer ORG.

The hole transport layer HTL is formed by using, e.g.1,3,5-Tris(3-methyldiphenylamino)-benzene (abbreviation: m-MTDAB). Thefilm thickness of the hole transport layer HTL is, e.g. 30 nm.

The red light emission layer EML1 is formed of a mixture of a first hostmaterial HM1 and a first dopant material EM1 whose emission light coloris red. The first dopant material EM1 is a red light-emitting materialwhich is formed of a luminescent organic compound or composition havinga central light emission wavelength in red wavelengths of the firstwavelength range. The red light emission layer EML1 is formed, forexample, by using 9, 9-bis (9-phenyl-9H-carbazole) fluorine(abbreviation: FL-2CBP) as the first host material HM1, and4-(dicyanomethylene)-2-methyl-6-(julolidin-4-yl-vinyl)-4H-pyran (DCM2)as the first dopant material EM1. The film thickness of the red lightemission layer EML1 is, e.g. 30 nm.

The green light emission layer EML2 is formed of a mixture of a secondhost material HM2 and a second dopant material EM2 whose emission lightcolor is green. The second dopant material EM2 is a green light-emittingmaterial which is formed of a luminescent organic compound orcomposition having a central light emission wavelength in greenwavelengths of the second wavelength range. The green light emissionlayer EML2 is formed, for example, by using FL-2CBP as the second hostmaterial HM2, and tris(8-hydroxyquinolato)aluminum (abbreviation: Alq₃)as the second dopant material EM2. The film thickness of the green lightemission layer EML2 is, e.g. 30 nm.

The blue light emission layer EML3 is formed of a mixture of a thirdhost material HM3 and a third dopant material EM3 whose emission lightcolor is blue. The third dopant material EM3 is a blue light-emittingmaterial which is formed of a luminescent organic compound orcomposition having a central light emission wavelength in bluewavelengths of the third wavelength range. The blue light emission layerEML3 is formed, for example, by using4,4′-bis(2,2′-diphenyl-ethen-1-yl)-diphenyl (BPVBI) as the third hostmaterial, and perylene as the third dopant material EM3. The filmthickness of the blue light emission layer EML3 is, e.g. 30 nm.

As the first host material HM1, second host material HM2 and third hostmaterial HM3, use may be made of 1,3,5-tris (carbazole-9-yl) benzene(abbreviation: TCP), aside from the above-described examples. Othermaterials may also be used.

Materials, other than the above-described examples, may be used as thefirst dopant material EM1, second dopant material EM2 and third dopantmaterial EM3. At least one of the first dopant material EM1, seconddopant material EM2 and third dopant material EM3 may be aphosphorescent material.

The characteristics which the material of the hole transport layer HTLis required to have are such absorbance spectrum characteristics as tohave an absorbance bottom on a shorter wavelength side than a firstabsorbance peak in absorbance spectrum characteristics of the firstdopant material EM1 and a second absorbance peak in absorbance spectrumcharacteristics of the second dopant material EM2.

A description is given of the principle for controlling the emissionlight colors in the first to third organic EL elements OLED1 to OLED3.

The band gap of the first dopant material EM1 is smaller than the bandgap of each of the second dopant material EM2 and third dopant materialEM3. The band gap of the second dopant material EM2 is smaller than theband gap of the third dopant material EM3. The band gap corresponds toan energy difference between a lowest unoccupied molecular orbital(LUMO) and a highest occupied molecular orbital (HOMO).

In the first organic EL element OLED1, since the band gap of the firstdopant material EM1 that is included in the red light emission layerEML1 is smallest, no energy transition occurs to other layers.Therefore, the first organic EL element OLED1 emits red light, andneither the green light emission layer EML2 nor blue light emissionlayer EML3 emits light.

In the second organic EL element OLED2, the first dopant material EM1 ofthe red light emission layer EML1 is in an optical quenching state. Theoptical quenching state refers to a state in which the dopant materialabsorbs ultraviolet and thus decomposition, polymerization or a changein molecular structure occurs in the dopant material, and, as a result,light emission does not occur or light emission hardly occurs. In thered light emission layer EML1 of the second organic EL element OLED2,the first dopant material EM1 emits no light. Even if the first dopantmaterial EM1 is in the optical quenching state, the band gap in the redlight emission layer EML1 is substantially equal to or less than theband gap prior to the optical quenching.

At this time, in the red light emission layer EML1 of the second organicEL element OLED2, the hole injectability or hole transportability of thered light emission layer EML1 increases by the ultraviolet irradiationfor the optical quenching of the first dopant material EM1, and the holemobility becomes higher than in the state prior to the ultravioletradiation. Hence, in the second organic EL element OLED2, the balancebetween electrons and holes varies, and the light emission positionshifts to the green light emission layer EML2. Therefore, the secondorganic EL element OLED2 emits green light, and the blue light emissionlayer EML3 emits no light.

In the third organic EL element OLED3, the first dopant material EM1 ofthe red light emission layer EML1 and the second dopant material EM2 ofthe green light emission layer EML2 are in the optical quenching state.In the red light emission layer EML1 of the third organic EL elementOLED3, the first dopant material EM1 emits no light. In addition, in thegreen light emission layer EML2 of the third organic EL element OLED3,the second dopant material EM2 emits no light. Even if the first dopantmaterial EM1 is in the optical quenching state, the band gap in the redlight emission layer EML1 is substantially equal to or less than theband gap prior to the optical quenching. In addition, even if the seconddopant material EM2 is in the optical quenching state, the band gap inthe green light emission layer EML2 is substantially equal to or lessthan the band gap prior to the optical quenching.

At this time, in the red light emission layer EML1 of the third organicEL element OLED3, like the second organic EL element OLED2, the holeinjectability or hole transportability increases. Similarly, in thegreen light emission layer EML2 of the third organic EL element OLED3,the hole injectability or hole transportability of the green lightemission layer EML2 increases by the ultraviolet irradiation for theoptical quenching of the second dopant material EM2, and the holemobility becomes higher than in the state prior to the ultravioletradiation. Hence, in the third organic EL element OLED3, the balancebetween electrons and holes further varies, and the light emissionposition shifts to the blue light emission layer EML3. Therefore, thethird organic EL element OLED3 emits blue light.

FIG. 4 schematically shows the cross-sectional structure of the displaypanel DP including the first to third organic EL elements OLED1 toOLED3. The cross-sectional structure shown in FIG. 4 does not includethe switching transistor.

As shown in FIG. 4, the gate insulation film GI, interlayer insulationfilm II and passivation film PS are interposed between the substrate SUBand the pixel electrode PE of each of the first to third organic ELelements OLED1 to OLED3. Each pixel electrode PE is disposed on thepassivation film PS.

The hole transport layer HTL is disposed on the pixel electrode PE ofeach of the first to third organic EL elements OLED1 to OLED3. The holetransport layer HTL extends over the first to third organic EL elementsOLED1 to OLED3. Specifically, the hole transport layer HTL is acontinuous film spreading over the display region, and is disposedcommon to the first to third organic EL elements OLED1 to OLED3. Inaddition, the hole transport layer HTL is disposed on each of thepartition walls PI which are disposed between the first organic ELelement OLED1 and second organic EL element OLED2, between the secondorganic EL element OLED2 and third organic EL element OLED3, and betweenthe third organic EL element OLED3 and first organic EL element OLED1.

The red light emission layer EML1 extends over the first to thirdorganic EL elements OLED1 to OLED3, and is disposed on the holetransport layer HTL. Specifically, the red light emission layer EML1 isa continuous film spreading over the display region, and is disposedcommon to the first to third organic EL elements OLED1 to OLED3. Inaddition, the red light emission layer EML1 is disposed on the holetransport layer HTL above the partition walls PI which are disposedbetween the first organic EL element OLED1 and second organic EL elementOLED2, between the second organic EL element OLED2 and third organic ELelement OLED3, and between the third organic EL element OLED3 and firstorganic EL element OLED1.

The green light emission layer EML2 extends over the first to thirdorganic EL elements OLED1 to OLED3, and is disposed on the red lightemission layer EML1. Specifically, the green light emission layer EML2is a continuous film spreading over the display region, and is disposedcommon to the first to third organic EL elements OLED1 to OLED3. Inaddition, the green light emission layer EML2 is disposed on the redlight emission layer EML1 above the partition walls PI which aredisposed between the first organic EL element OLED1 and second organicEL element OLED2, between the second organic EL element OLED2 and thirdorganic EL element OLED3, and between the third organic EL element OLED3and first organic EL element OLED1.

The blue light emission layer EML3 extends over the first to thirdorganic EL elements OLED1 to OLED3, and is disposed on the green lightemission layer EML2. Specifically, the blue light emission layer EML3 isa continuous film spreading over the display region, and is disposedcommon to the first to third organic EL elements OLED1 to OLED3. Inaddition, the blue light emission layer EML3 is disposed on the greenlight emission layer EML2 above the partition walls PI which aredisposed between the first organic EL element OLED1 and second organicEL element OLED2, between the second organic EL element OLED2 and thirdorganic EL element OLED3, and between the third organic EL element OLED3and first organic EL element OLED1.

The counter-electrode CE extends over the first to third organic ELelements OLED1 to OLED3, and is disposed on the blue light emissionlayer EML3. Specifically, the counter-electrode CE is a continuous filmspreading over the display region, and is disposed common to the firstto third organic EL elements OLED1 to OLED3. In addition, thecounter-electrode CE is disposed on the blue light emission layer EML3above the partition walls PI which are disposed between the firstorganic EL element OLED1 and second organic EL element OLED2, betweenthe second organic EL element OLED2 and third organic EL element OLED3,and between the third organic EL element OLED3 and first organic ELelement OLED1.

The first to third organic EL elements OLED1 to OLED3 are sealed byusing the sealing substrate SUB2.

FIG. 5 shows normalized light absorbance spectrum characteristics ofDCM2 that is the first dopant material EM1, Alq₃ that is the seconddopant material EM2, and m-MTDAB that is the material of which the holetransport layer HTL is formed. The light absorbance spectrumcharacteristics indicate the absorbance of each material, which iscalculated on the basis of the transmittance of each material at a timewhen reference light in a wavelength range between 275 nm to 650 nm isradiated on each material. The normalized light absorbance spectrumcharacteristics are calculated on the assumption that the maximum valueof the absorbance in the wavelength range of 275 nm to 650 nm is 1.0,i.e. the normalized absorbance.

The first dopant material EM1 has absorbance spectrum characteristicswhich are indicated by (a) in FIG. 5, and has a first absorbance peak inthe vicinity of the wavelength of 500 nm. The second dopant material EM2has absorbance spectrum characteristics which are indicated by (b) inFIG. 5, and has a second absorbance peak in the vicinity of thewavelength of 400 nm.

The hole transport layer HTL has absorbance spectrum characteristicswhich are indicated by (c) in FIG. 5, and has a third absorbance peak inthe vicinity of the wavelength of 300 nm and a substantial absorbancebottom at the wavelength of 345 nm.

In the absorbance spectrum characteristics, the absorbance peak is apoint at which the absorbance at wavelengths of 300 nm or more takes amaximum value, that is, at which the normalized absorbance is 1.0. Onthe other hand, the absorbance bottom corresponds to a point where thenormalized absorbance decreases to a minimum in the absorbance spectrumcharacteristics. In the case where the absorbance spectrumcharacteristics have substantially an L shape curve, as in the exampleshown in FIG. 5, the point at which the normalized absorbance decreasesto 10% or less is the absorbance bottom. In the case where thenormalized absorbance is 10% or less in a region corresponding to thebottom side of the L shape, the point at which the normalized absorbanceis 10% on the shortest wavelength side is set to be the absorbancebottom.

FIG. 6 shows the case in which the normalized absorbance once decreasesto 10% or less at a point A on the shorter wavelength side in the regioncorresponding to the bottom side of the L shape, then increasing above10% on the longer wavelength side, and decreasing once again to 10% orless at a point B on the longer wavelength side. In this case, the pointB, at which the normalized absorbance decreases to 10% on the longestwavelength side, is set to be the absorbance bottom.

In short, in the normalized absorbance spectrum characteristics, thenormalized absorbance on the longer wavelength side than the absorbancebottom is 10% or less.

As regards the m-MTDAB that is the material of the hole transport layerHTL, on the shorter wavelength side than the wavelength of 345 nm, thenormalized absorbance is more than 10%. On the other hand, on the longerwavelength side than the wavelength of 345 nm, the normalized absorbanceis 10% or less. Thus, the absorbance bottom of the m-MTDAB occurs on theshorter wavelength side than the first absorbance peak (about 500 nm) ofthe first dopant material EM1 and the second absorbance peak (about 400nm) of the second dopant material EM2.

In FIG. 5, (a) and (b)indicate the absorbance spectrum characteristicsin the state in which no optical quenching occurs in the first dopantmaterial EM1 and second dopant material EM2. In the absorbance spectrumcharacteristics in the state in which optical quenching occurs in thefirst dopant material EM1 and second dopant material EM2, the absorbancepeaks may slightly become lower than in the state before the opticalquenching, or the wavelengths at which the absorbance peaks occur mayslightly vary. However, the absorption peaks do not greatly vary,compared to the state before the optical quenching. In particular, thewavelengths at which the absorbance peaks occur do not shift to theshorter wavelength side than the absorbance bottom of the hole transportlayer HTL.

Although not shown, in the case where the absorbance spectrumcharacteristics have substantially a U shape curve, that part of the Ushape curve, which has a lowest normalized absorbance, is set to be theabsorbance bottom.

Next, referring to a flow chart of FIG. 7, a description is given of anexample of a manufacturing method of the first to third organic ELelements OLED1 to OLED3.

To start with, in an array process, a pixel electrode PE is formed on apassivation film.

Then, in an EL process, a hole transport layer HTL is formed on thepixel electrode PE by a vacuum evaporation method by using a rough maskin which an opening corresponding to the display region is formed. InFIG. 7, this step is indicated by “HTL EVAPORATION”.

Subsequently, a red light emission layer EML1 including a first dopantmaterial EM1 is formed by a vacuum evaporation method by using a roughmask in which an opening corresponding to the display region is formed.In FIG. 7, this step is indicated by “EML1 EVAPORATION”.

Then, regions, which correspond to the pixel PX2 in which the secondorganic EL element OLED2 is formed and the pixel PX3 in which the thirdorganic EL element OLED3 is formed, are irradiated with light in a rangeof wavelengths of about 360 to 800 nm with an intensity in a range of0.001 to 1.0 mW·mm⁻²nm⁻¹. In this example, the intensity of irradiationlight is set at about 0.1 mW·mm⁻²·nm⁻¹. In FIG. 7, this step isindicated by “PHOTO1 EXPOSURE”.

In the exposure step indicated by “PHOTO1 EXPOSURE”, in the pixels PX2and PX3 which are irradiated with light with the wavelengths of about360 to 800 nm, the first dopant material EM1 in the red light emissionlayer EML1 absorbs the irradiation light since the first dopant materialEM1 has a first absorbance peak in the vicinity of 500 nm. Thereby,optical quenching occurs in the first dopant material EM1 due todecomposition, polymerization or a change in molecular structure. On theother hand, in the pixels PX2 and PX3, the normalized absorbance of thehole transport layer HTL in the wavelength range of irradiation light isrelatively low and is 10% or less. Thus, even if the hole transportlayer HTL absorbs the irradiation light, there hardly occursdecomposition, polymerization or change in molecular structure.

Subsequently, a green light emission layer EML2 including a seconddopant material EM2 is formed by a vacuum evaporation method by using arough mask in which an opening corresponding to the display region isformed. In FIG. 7, this step is indicated by “EML2 EVAPORATION”.

Then, the region, which corresponds to the pixel PX3, is irradiated withlight in a range of wavelengths of about 360 to 800 nm with an intensityin a range of 0.001 to 1.0 mW·mm⁻²·nm⁻¹. In this example, the intensityof irradiation light is set at about 0.1 mW·mm⁻²·nm⁻¹. In FIG. 7, thisstep is indicated by “PHOTO2 EXPOSURE”. In the meantime, ultravioletlights with different wavelengths may be radiated in the “PHOTO1EXPOSURE” and “PHOTO2 EXPOSURE”.

In the exposure step indicated by “PHOTO2 EXPOSURE”, in the pixel PX3which is irradiated with light with the wavelengths of about 360 to 800nm, the second dopant material EM2 in the green light emission layerEML2 absorbs the irradiation light since the second dopant material EM2has a second absorbance peak in the vicinity of 400 nm. Thereby, opticalquenching occurs in the second dopant material EM2 due to decomposition,polymerization or a change in molecular structure. On the other hand, inthe pixel PX3, the normalized absorbance of the hole transport layer HTLin the wavelength range of irradiation light is relatively low and is10% or less. Thus, even if the hole transport layer HTL absorbs theirradiation light, there hardly occurs decomposition, polymerization orchange in molecular structure.

Subsequently, a blue light emission layer EML3 including a third dopantmaterial EM3 is formed on the green light emission layer EML2 by avacuum evaporation method by using a rough mask in which an openingcorresponding to the display region is formed. In FIG. 7, this step isindicated by “EML3 EVAPORATION”.

Then, a counter-electrode CE is formed on the blue light emission layerEML3. In FIG. 7, this step is indicated by “CE EVAPORATION”.

Thereafter, a step of sealing by the sealing substrate SUB2 isperformed.

As shown in FIG. 8, in the exposure step indicated by “PHOTO1”, light isradiated by using a photomask MASK1 which shields the pixel PX1 fromlight and has an opening facing the pixels PX2 and PX3. Thereby, in thered light emission layer EML1 that is formed in the preceding step, thefirst dopant material EM1 of the red light emission layer EML1 that isformed in the pixels PX2 and PX3 absorbs light and transitions into anoptical quenching state.

In the subsequent exposure step indicated by “PHOTO2”, light is radiatedby using a photomask MASK2 which shields the pixel PX1 and pixel PX2from light and has an opening facing the pixel PX3. Thereby, in thegreen light emission layer EML2 that is formed in the preceding step,the second dopant material EM2 of the green light emission layer EML2that is formed in the pixel PX3 absorbs light and transitions into anoptical quenching state.

As described above, the hole transport layer HTL, red light emissionlayer EML1, green light emission layer EML2 and blue light emissionlayer EML3 are the continuous films extending over the first to thirdorganic EL elements OLED1 to OLED3. Similarly, the counter-electrode CEis the continuous film extending over the first to third organic ELelements OLED1 to OLED3. Thus, when these films are formed by theevaporation method, a fine mask in which a fine opening is formed isneedless, and the manufacturing cost of the mask can be reduced. Inaddition, when these films are formed, the amount of material depositedon the mask decreases, and the efficiency of use of the material of thefilms is enhanced. Moreover, since there is no need to selectively applythe light-emitting materials, a defect of color mixture can beprevented.

Besides, the second organic EL element OLED2 emits green light since thefirst dopant material EM1 of the red light emission layer EML1 is in theoptical quenching state. The third organic EL element OLED3 emits bluelight since the first dopant material EM1 of the red light emissionlayer EML1 and the second dopant material EM2 of the green lightemission layer EML2 are in the optical quenching state. Accordingly,full-color display with high fineness can be realized.

When optical quenching is caused in the first dopant material EM1 of thered light emission layer EML1 and the second dopant material EM2 of thegreen light emission layer EML2, the productivity of the organic ELdisplay device can be more improved as the exposure time in the PHOTO1exposure and PHOTO2 exposure is shorter.

As means for shortening the exposure time, there is a method ofincreasing the intensity of exposure. The radiation light wavelength ofa high-pressure mercury lamp, which is a light source of a generalexposure device, is in the range of 200 to 600 nm, and the peakwavelength, at which the emission light intensity takes a maximum value,is 365 nm in the emission light spectrum characteristics.

If all wavelengths of the radiation light of the high-pressure mercurylamp are utilized for exposure, the radiation intensity increases, butthe wavelengths include wavelengths of light which is absorbed by notonly the first dopant material EM1 and second dopant material EM2, butalso the hole transport layer HTL. Consequently, there may possiblyoccur decomposition, polymerization or a change in molecular structurein the hole transport layer HTL. Consequently, it is possible that thehole transportability of the hole transport layer HTL decreases, andsuch a problem arises that the performance of the organic EL displaydevice deteriorates.

It is thinkable to radiate light of wavelengths, which is hardlyabsorbed by the hole transport layer HTL but is absorbed by only thefirst host material HM1 and second host material HM2. In such a case,however, an optical element for selecting wavelengths is needed. Inaddition, at the time of exposure, the radiation intensity decreases dueto the limitation of radiation wavelengths, and also the radiationintensity at the time when the radiation light passes through theoptical element decreases due to, e.g. absorption of light by theoptical element itself. Consequently, since the exposure intensitydecreases and the exposure time increases, the productivity may possiblydeteriorate.

Decomposition, polymerization or change in molecular structure issuppressed in the hole transport layer HTL by radiating light that haswavelengths, which are longer than the absorbance bottom in theabsorbance spectrum characteristics of the hole transport layer HTL, asthe wavelengths of light for use in the exposure steps of “PHOTO1EXPOSURE” and “PHOTO2 EXPOSURE”.

On the other hand, the first dopant material EM1 and second dopantmaterial EM2, which are to be set in the optical quenching state, haveabsorption peaks in the absorbance spectrum characteristics on thelonger wavelength side than the absorbance bottom of the hole transportlayer HTL. Thus, in the exposure steps of “PHOTO1 EXPOSURE” and “PHOTO2EXPOSURE”, light is radiated which has the wavelengths includingwavelengths in the vicinity of the absorbance bottom of the holetransport layer HTL, and wavelengths longer than these wavelengths inthe vicinity of the absorbance bottom.

Specifically, as the exposure wavelengths in each exposure step, use canbe made of the wavelengths in the range longer than the wavelengths inthe ultraviolet range (200 to 400 nm) at which the normalized absorbanceof the hole transport layer HTL is 10% or less, and all wavelengths inthe visible light range. This wavelength range includes the peakwavelength of the high-pressure mercury lamp that is the light source.Therefore, the exposure intensity can be kept at a high level, and theproductivity can be improved by the decrease in exposure time.

A description is given of examples of variations of elements, which canbe adopted in the first to third organic EL elements OLED1 to OLED3 inthe present embodiment.

For example, the organic layer ORG of each of the first to third organicEL elements OLED1 to OLED3 may include a hole injection layer on thepixel electrode side. In this case, the hole injection layer is disposedon the pixel electrode PE, and the hole transport layer HTL is disposedon the hole injection layer. In addition, the organic layer ORG of eachof the first to third organic EL elements OLED1 to OLED3 may include anelectron injection layer and an electron transport layer on thecounter-electrode side. In this case, the electron transport layer isdisposed on the blue light emission layer EML3, and the electroninjection layer is disposed on the electron transport layer. The holeinjection layer, electron injection layer and electron transport layer,like the hole transport layer HTL, can be formed by a vacuum evaporationmethod by using a rough mask.

The pixel electrode PE of each of the first to third organic EL elementsOLED1 to OLED3 may have a two-layer structure in which a reflectivelayer and a transmissive layer are stacked, or may have a singletransmissive layer structure or a single reflective layer structure. Thereflective layer can be formed of a light-reflective, electricallyconductive material such as silver (Ag) or aluminum (Al). Thelight-transmissive layer can be formed of a light-transmissive,electrically conductive material such as indium tin oxide (ITO) orindium zinc oxide (IZO). In the case where the pixel electrode PE hasthe two-layer structure comprising the reflective layer and transmissivelayer, the reflective layer is disposed on the passivation film PS, andthe transmissive layer is disposed on the reflective layer.

The counter-electrode CE may have a two-layer structure in which asemi-transmissive layer and a transmissive layer are stacked, or mayhave a single transmissive layer structure or a single semi-transmissivelayer structure. The semi-transmissive layer can be formed of anelectrically conductive material such as magnesium or silver. Thetransmissive layer can be formed of a light-transmissive, electricallyconductive material such as ITO or IZO.

The first to third organic EL elements OLED1 to OLED3 may adopt atop-emission-type structure in which emission light is extracted fromthe counter-electrode side. In this case, the pixel electrode PE of eachof the first to third organic EL elements OLED1 to OLED3 includes atleast a reflective layer.

As is shown in FIG. 9, the first to third organic EL elements OLED1 toOLED3 may adopt a micro-cavity structure which comprises a pixelelectrode PE having a reflective layer PER, and a counter-electrode CEwhich is formed of a semi-transmissive layer. In this case, the pixelelectrode PE has a two-layer structure including the reflective layerPER, and a transmissive layer PET which is disposed between thereflective layer PER and the hole transport layer HTL. In the first tothird organic EL elements OLED1 to OLED3, the organic layer ORG, whichis disposed between the transmissive layer PET and the counter-electrodeCE, includes, like the example shown in FIG. 3, the hole transport layerHTL, red light emission layer EML1, green light emission layer EML2 andblue light emission layer EML3. According to this structure, atop-emission-type micro-cavity structure is realized. In the case whereone of the pixel electrode PE and the counter-electrode CE, whichsandwich the organic layer ORG, is composed of a transparent electrodealone, a micro-cavity structure cannot be obtained.

In the case where the micro-cavity structure is adopted, alight-transmissive thin film, for instance, silicon oxynitride (SiON) orITO, may be disposed on the counter-electrode CE. Such a thin film isusable as a protection film for protecting the first to third organic ELelements OLED1 to OLED3, and is also usable as an optical matching layerfor adjusting the optical path length for optimizing opticalinterference. Moreover, a light-transmissive insulation film, forinstance, silicon nitride (SiN), may be disposed between the reflectivelayer of the pixel electrode PE and the semi-transmissive layer of thecounter-electrode CE. Such an insulation film is usable as an adjustinglayer for adjusting an optical interference condition. The optical pathlength of such an adjusting layer is set at a least common multiple of ¼of the wavelength of emission light of each of the first to thirdorganic EL elements OLED1 to OLED3. Such an adjusting layer may bedisposed only in the first organic EL element OLED1 and the secondorganic EL element OLED2.

Of the first to third organic EL elements OLED1 to OLED3, at least thefirst organic EL element OLED1 and the second organic EL element OLED2may include an irregular scattering layer which is disposed between thepixel electrode PE and the passivation film PS.

In the present embodiment, the description has been given of the case inwhich the hole injectability or hole transportability in the red lightemission layer EML1 and green light emission layer EML2 is increased bythe ultraviolet irradiation for causing optical quenching in the firstdopant material EM1 of the red light emission layer EML1 and the seconddopant material EM2 of the green light emission layer EML2.Alternatively, the same advantageous effect can be obtained in the casein which the hole injectability or hole transportability in the redlight emission layer EML1 and green light emission layer EML2 isdecreased by the ultraviolet irradiation.

A description is given of examples of variations which can be adopted inthe manufacturing method of the first to third organic EL elements OLED1to OLED3.

The exposure step that is indicated by “PHOTO1 EXPOSURE” may beperformed at any timing, if the timing is after the step of forming thered light emission layer EML1, which is indicated by “EML1 EVAPORATION”.For example, the exposure step indicated by “PHOTO1 EXPOSURE” may beperformed after the step of forming the green light emission layer EML2which is indicated by “EML2 EVAPORATION”, or after the step of formingthe blue light emission layer EML3 which is indicated by “EML3EVAPORATION”, or after the step of forming the counter-electrode CEwhich is indicated by “CE EVAPORATION”.

The exposure step that is indicated by “PHOTO2 EXPOSURE” may beperformed at any timing, if the timing is after the step of forming thegreen light emission layer EML2, which is indicated by “EML2EVAPORATION”. For example, the exposure step indicated by “PHOTO2EXPOSURE” may be performed after the step of forming the blue lightemission layer EML3 which is indicated by “EML3 EVAPORATION”, or afterthe step of forming the counter-electrode CE which is indicated by “CEEVAPORATION”.

In the case of the structure in which the organic layer ORG of each ofthe first to third organic EL elements OLED1 to OLED3 includes theelectron transport layer, a step of forming the electron transport layermay be added after the step of forming the blue light emission layerEML3 which is indicated by “EML3 EVAPORATION”.

In the present embodiment, the description has been given of the case inwhich two exposure steps indicated by “PHOTO1 EXPOSURE” and “PHOTO2EXPOSURE” are performed. Alternatively, by making use of a halftonemask, optical quenching may be caused in the first dopant material EM1and second dopant material EM2 by a single exposure step. This halftoneexposure step may be performed at any timing, if the timing is after thestep of forming the green light emission layer EML2. The halftone mask,which is used in this case, has different transmittances correspondingto the respective regions where the first to third organic EL elementsOLED1 to OLED3 are to be formed. Specifically, the transmittancecorresponding to the region where the third organic EL element OLED3 isto be formed is higher than the transmittance corresponding to theregion where the second organic EL element OLED2 is to be formed. Thetransmittance corresponding to the region where the second organic ELelement OLED2 is to be formed is higher than the transmittancecorresponding to the region where the first organic EL element OLED1 isto be formed. Thereby, the exposure step is simplified, and theproductivity is improved.

In the exposure steps indicated by “PHOTO1 EXPOSURE” and “PHOTO2EXPOSURE”, it is preferable that the oxygen concentration in theexposure device be set at 20 ppm. Under this condition of the oxygenconcentration, the optical quenching in the first dopant material EM1and second dopant material EM2 is promoted.

For example, FL-2CBP is used as the host material,tri(2-phenylpyridine)iridium (III) (abbreviation: Ir(ppy)3) is used asthe dopant material, and a thin film with a thickness of 30 nm and adopant concentration of 8% is formed on a glass substrate by a vacuumevaporation method. Light of 355 nm or more was radiated for 10 minuteson this formed thin film by using a mercury xenon lamp light source,both in the environment in which the oxygen concentration is 1 ppm orless and the environment in which the oxygen concentration is 20 ppm.

Before and after the light radiation, the photoluminescence intensity(PL intensity) was compared by a photoluminescence method. In the casewhere the PL intensity before the light radiation is assumed to be 100%,the PL intensity decreased to 49% after the light radiation in theenvironment in which the oxygen concentration is 1 ppm, and the PLintensity decreased to 38% after the light radiation in the environmentin which the oxygen concentration is 20 ppm.

It can be assumed that the decrease in PL intensity by the lightradiation occurs due to the optical quenching of the dopant material.Therefore, in the exposure steps indicated by “PHOTO1 EXPOSURE” and“PHOTO2 EXPOSURE”, by performing the exposure in the environment inwhich the oxygen concentration is 20 ppm or more, the optical quenchingof the dopant material can be caused in a shorter time, and theproductivity can be enhanced.

The present invention is not limited directly to the above-describedembodiments. In practice, the structural elements can be modified andembodied without departing from the spirit of the invention. Variousinventions can be made by properly combining the structural elementsdisclosed in the embodiments. For example, some structural elements maybe omitted from all the structural elements disclosed in theembodiments. Furthermore, structural elements in different embodimentsmay properly be combined.

In the above-described embodiment, the organic EL display deviceincludes three kinds of organic EL elements with different emissionlight colors, namely, the first to third organic EL elements OLED1 toOLED3. Alternatively, the organic EL display device may include, asorganic EL elements, only two kinds of organic EL elements withdifferent emission light colors, or four or more kinds of organic ELelements with different emission light colors.

In the present embodiment, the description has been given of the case inwhich when the dopant material is in an optical quenching state, nolight is emitted at all from the dopant material. However, if the sameadvantageous effect can be obtained, the invention is applicable to thecase in which when the dopant material is in an optical quenching state,light is hardly emitted from the dopant material.

1. A method of manufacturing an organic EL device, comprising: forming afirst pixel electrode, a second pixel electrode, and a third pixelelectrode on an insulative substrate; forming a hole transport layer ofa material having an absorbance bottom, commonly above the first tothird pixel electrodes; forming a first light emission layer whichincludes a first dopant material having a first absorbance peak inabsorbance spectrum characteristics of the first dopant material, abovethe hole transport layer and commonly above the first to third pixelelectrodes; exposing a region of the first light emission layer which isabove the second pixel electrode and the third pixel electrode tooptically quench the first dopant material in the region; forming asecond light emission layer which includes a second dopant materialhaving a second absorbance peak in absorbance spectrum characteristicsof the second dopant material, above the first light emission layer andcommonly above the first to third pixel electrodes; exposing a region ofthe second light emission layer which is disposed above the third pixelelectrode to optically quench the second dopant material in the region;forming a third light emission layer which includes a third dopantmaterial, above the second light emission layer and commonly above thefirst to third pixel electrodes; and forming a counter-electrode abovethe third light emission layer.
 2. The method according to claim 1,wherein the forming the hole transport layer includes forming a holetransport layer which is formed of a material having an absorbancebottom on a shorter wavelength side than the first absorbance peak ofthe first dopant material and the second absorbance peak of the seconddopant material in absorbance spectrum characteristics of the holetransport layer.
 3. The method according to claim 2, wherein theexposing the region of the first light emission layer comprisesradiating light to the first light emission layer through a photomaskwhich shields the first pixel electrode from the light and has anopening facing the region above the second pixel electrode and the thirdpixel electrode.
 4. The method according to claim 3, wherein theexposing the region of the first light emission layer comprisesradiating light which has wavelengths longer than the absorbance bottomin the absorbance spectrum characteristics of the hole transport layer.5. The method according to claim 4, wherein the exposing the region ofthe first light emission layer comprises radiating light which haswavelengths in a range longer than the wavelengths in a ultravioletrange at which a normalized absorbance of the hole transport layer is10% or less, and all wavelengths in a visible light range.
 6. The methodaccording to claim 3, wherein the exposing the region of the secondlight emission layer comprises radiating light to the second lightemission layer through a photomask which shields the first and secondpixel electrodes from the light and has an opening facing the regionabove the third pixel electrode.
 7. The method according to claim 5,wherein the exposing the region of the second light emission layercomprises radiating light which has wavelengths longer than theabsorbance bottom in the absorbance spectrum characteristics of the holetransport layer.
 8. The method according to claim 7, wherein theexposing the region of the second light emission layer comprisesradiating light which has wavelengths in a range longer than thewavelengths in a ultraviolet range at which a normalized absorbance ofthe hole transport layer is 10% or less, and all wavelengths in avisible light range.
 9. The method according to claim 1, furthercomprising forming a partition wall between the first, second, and thirdpixel electrodes at a time before the forming the first light emissionlayer.
 10. A method of manufacturing an organic EL device, comprising:forming a first pixel electrode, a second pixel electrode, and a thirdpixel electrode on an insulative substrate; forming a hole transportlayer commonly above the first to third pixel electrodes; forming afirst light emission layer which includes a first dopant material havinga first absorbance peak in absorbance spectrum characteristics of thefirst dopant material, above the hole transport layer and commonly abovethe first to third pixel electrodes; exposing a region of the firstlight emission layer which is above the second pixel electrode and thethird pixel electrode to optically quench the first dopant material inthe region; forming a second light emission layer which includes asecond dopant material having a second absorbance peak in absorbancespectrum characteristics of the second dopant material, above the firstlight emission layer and commonly above the first to third pixelelectrodes, the hole transport layer having an absorbance bottom on ashorter wavelength side than the first absorbance peak of the firstdopant material and the second absorbance peak of the second dopantmaterial in absorbance spectrum characteristics of the hole transportlayer; exposing a region of the second light emission layer which isdisposed above the third pixel electrode to optically quench the seconddopant material in the region; forming a third light emission layerwhich includes a third dopant material, above the second light emissionlayer and commonly above the first to third pixel electrodes; andforming a counter-electrode above the third light emission layer.
 11. Amethod of manufacturing an organic EL device, comprising: forming afirst pixel electrode, a second pixel electrode, and a third pixelelectrode on an insulative substrate; forming a hole transport layercommonly above the first to third pixel electrodes; forming a firstlight emission layer which includes a first dopant material having afirst absorbance peak in absorbance spectrum characteristics of thefirst dopant material, above the hole transport layer and commonly abovethe first to third pixel electrodes; exposing a region of the firstlight emission layer which is above the second pixel electrode and thethird pixel electrode to optically quench the first dopant material inthe region; forming a second light emission layer which includes asecond dopant material having a second absorbance peak in absorbancespectrum characteristics of the second dopant material, above the firstlight emission layer and commonly above the first to third pixelelectrodes, the hole transport layer which has an absorbance bottom, atwhich a normalized absorbance is 10% or less, on a shorter wavelengthside than the first absorbance peak of the first dopant material and thesecond absorbance peak of the second dopant material in normalizedabsorbance spectrum characteristics of the hole transport layer, thehole transport layer extending over the first to third organic ELelements and being disposed between the pixel electrode and the firstlight emission layer; exposing a region of the second light emissionlayer which is disposed above the third pixel electrode to opticallyquench the second dopant material in the region; forming a third lightemission layer which includes a third dopant material, above the secondlight emission layer and commonly above the first to third pixelelectrodes; and forming a counter-electrode above the third lightemission layer.
 12. The method according to claim 11, wherein theexposing the region of the first light emission layer comprisesradiating light to the first light emission layer through a photomaskwhich shields the first pixel electrode from the light and has anopening facing the region above the second pixel electrode and the thirdpixel electrode.
 13. The method according to claim 12, wherein theexposing the region of the first light emission layer comprisesradiating light which has wavelengths longer than the absorbance bottomin the absorbance spectrum characteristics of the hole transport layer.14. The method according to claim 11, wherein the exposing the region ofthe second light emission layer comprises radiating light to the secondlight emission layer through a photomask which shields the first andsecond pixel electrodes from the light and has an opening facing theregion above the third pixel electrode.
 15. The method according toclaim 14, wherein the exposing the region of the second light emissionlayer comprises radiating light which has wavelengths longer than theabsorbance bottom in the absorbance spectrum characteristics of the holetransport layer.